在sql server中连接表？

Question

在SQL Server中，我加入了如下所示的三个表。

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
left outer join table3 t3 on t1.empid = t2.empid 
    and t2.id= t3.id 

这是正确的，我用and的条件，谢谢。

，如果我写的PROC：我正在使用joing左外部表连接

select wrh.empid 
from Tbl_F_Weekly_Report_Header WRH 
left outer join Tbl_Emp_Master_M EM on wrh.EmpId =em.EmpId 
LEFT outer join Tbl_F_Emp_Position_M EPS on WRH.PositionCode = EPS.PositionCode 
where EM [Tbl_Emp_Master_M] doesnot contain Positioncode 

是正确

Answer 1

你LEFT OUTER JOIN上表3是不正确。你只需要：

SELECT t1.empid, t2.sales, t3.date 
FROM table1 AS t1 
LEFT OUTER JOIN table2 AS t2 ON t1.empid = t2.empid 
LEFT OUTER JOIN table3 AS t3 ON t2.id = t3.id 

，因为你已经在第一LEFT OUTER JOIN

你更新的查询指定上述t1.empid = t2.empid：

SELECT wrh.empid 
FROM Tbl_F_Weekly_Report_Header AS wrh 
LEFT OUTER JOIN Tbl_Emp_Master_M AS em ON wrh.EmpId = em.EmpId  
LEFT OUTER JOIN Tbl_F_Emp_Position_M AS eps ON wrh.PositionCode = eps.PositionCode 

看起来不错，只要确定你包括FROM（最初失踪从你的问题）

Answer 2

你刚刚错过选择>选择和t3左外连接。您必须使用SQL Server Management Studio来测试您的查询。

select 
t1.empid, 
t2.sales, 
t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid=t2.empid 
left outer join table3 t3 on t2.id= t3.id 

问候

Answer 3

是你的SQL语句是正确的。但你可以试试这个：

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
inner join table3 t3 on t2.empid = t3.empid 

或

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
left outer join table3 t3 on t2.empid = t3.empid